Goldman Sachs compliance conducted a review of transactions made by an employee who generated $250 million trading junk bonds, and found that the trades complied in full with the Volcker Rule - i.e., did not violate a ban on buying and selling for the bank’s own account. The review was carried out to ensure the company could defend them against regulatory scrutiny.

Thomas Malafronte attracted attention last month when news reports said he generated more than $100 million earlier this year by trading the debt of junk-rated energy firms and retailers. That prompted questions about whether he complied with the Volcker Rule, part of the 2010 Dodd-Frank Act aimed at preventing banks from wagering money in ways that don’t benefit clients. By the start of last month, Malafronte’s revenue had swelled to about $250 million - probably ranking him among the most successful traders this year across all major Wall Street banks.

In addition to examining Malafronte’s transactions, compliance employees at Goldman Sachs contacted executives in his credit-trading group, compiled documentation, and prepared material to show regulators.

Goldman Sachs isn’t alone in generating large trading gains. A team of Citigroup Inc. traders on the U.S. dollar interest-rate swaps desk led by Geoff Weber in New York generated about $300 million of revenue this year, thriving by serving companies and investors trying to anticipate central bank decisions, people familiar with the matter said last month.